处理过程
配置举例：
预留vlan3500（for example）
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vlan batch 3 10 20 100 300 to 301 3000 to 3002 3500 4000
#
观察端口
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observe-port 1 interface GigabitEthernet0/0/21 vlan 3500
#
三个镜像端口：
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interface GigabitEthernet0/0/3
port-mirroring to observe-port 1 both
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interface GigabitEthernet0/0/4
port-mirroring to observe-port 1 both
#
interface GigabitEthernet0/0/5
port-mirroring to observe-port 1 both
#
三个观察端口：
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interface GigabitEthernet0/0/11
port link-type trunk
undo port trunk allow-pass vlan 1
port trunk allow-pass vlan 3500
#
interface GigabitEthernet0/0/12
port link-type trunk
undo port trunk allow-pass vlan 1
port trunk allow-pass vlan 3500
#
interface GigabitEthernet0/0/13
port link-type trunk
undo port trunk allow-pass vlan 1
port trunk allow-pass vlan 3500
#
环回端口：
#
interface GigabitEthernet0/0/21
description neibuhuanhui
loopback internal
mac-address learning disable
port link-type trunk
undo port trunk allow-pass vlan 1
port trunk allow-pass vlan 3500
stp disable
建议与总结
实现原理：将所有端口镜像报文引入一个观察端口，通过观察端口内部环回（配置loopback internal），将报文在vlan内广播道其它若干实际观察端口，报文出端口时剥除vlan id。
注意：如果交换机全局配置stp enable，需要在环回端口上配置stp disable，否则该端口如果接收到交换机自己发出去的stp报文，会将端口置为discarding状态，环回报文都会在入向被丢弃
